3 Quality Control Flashcards
True or false - QC activities only take place in analytical activities?
False - QC activities also takes place outside of analytical activities (ex - transcribing the correct information in pre - analytical)
What are the 2 types of statistical quality control?
- Statistical QCs - running controlled samples - has known value with patients’ samples, using control charts. is use to detect error in the procedure
- Non- statistical QC - procedures in place that maintains and improve performance like calibrating, doing monthly maintenance is used to maintain and improve performance
Define analytical run
Is a set interval at which the performance (accuracy and precision) of an analyte is to remain stable. Can is defined by time
Define control range
Is the acceptable range of QC values considering normal day to day variations. It is established for each analyte using statistical procedures
What does it mean when a QC value falls outside of the control range?
That means that an error is present in the analytical system
How many measurements over how many days should be used to establish an initial control range?
A minimum of 20 measurements over at least 10 days
In a normal Gaussian distribution, which range is most often selected as the limit for control range?
The -/+ 2s range
What does the -/+ 2s range mean? What is another name for the -/+ 2s range?
It means that 95% of the control values will fall in between the -/+ 2s range. Another name for the -/+ 2s range is the 95% confidence interval
What are quality control charts/ Levey - Jennings charts used for?
To quickly review and inspect the control data
If a control value falls out of the range, what are the 4 things to do?
- Document the control value
- Investigate/ resolve the out of control value
- Write a corrective action
- Rerun if necessary Control values must be in range unless if it is a 1 2s warning rule
Overtime, what do the patterns in control chart reveal?
The types of errors present in the method - this can assist in isolating the resolving the source of the error
On a control chart, what does random error look like? What is random error associated with?
It will look like increased/ a wide scattered on a control chart
Random error is associated with decreased precision
Where does random error come from?
From unpredictable sources in a method
What does systematic error look like on a control chart?
What is systematic error associated with?
Systematic error will look like a shift / a trend (can be increase or decrease) in the chart
Systematic error is associated with decrease accuracy
Where does systematic error come from?
From sources that have consistent effects on the control values/ QCs being ran
